Capacitors of the type mentioned above are known from publication WO 01/16973, which are tantalum electrolyte capacitors in chip construction. The known capacitors feature a sheet-shaped anode contact that extends outwardly from the anode body, exiting the anode body from a face of the housing. From the point of exit from the housing, the anode contact is bent in the direction of the base surface. At the edge between the face and the base surface, the anode is bent inward a second time, forming a soldering surface at the base surface of the housing. On another face of the housing, a cathode contact extends outwardly from the housing and is also bent several times, so that a corresponding soldering surface for the anode contact is also present on the underside of the housing. Using the two soldering surfaces, the component can be soldered onto a printed circuit board in chip construction.
A drawback of known capacitors is that the anode contact, which is made from a tantalum sheet, is not easily soldered by means of soft soldering. To create a permanent and conductive connection to a printed circuit board, the tantalum sheet must be designed to be capable of being soldered and glued. However, tantalum surfaces are poorly wettable or not wettable at all with the solders normally used in joining technology. For this reason, a surface made of tantalum cannot be soldered without additional treatment.
Therefore, extensive measures are necessary to obtain a soldering surface that is based on this tantalum sheet and provided on the underside of the housing. One measure for making the tantalum sheet solderable would be, for example, chemical or electrochemical nickel-plating or tin-plating, in which the housing surface surrounding the soldering surface is also metal-coated so as to ensure the adhesive capacity of the solder and an adequate frictional connection between the component and a printed circuit board underneath it. This form of tin-plating contact elements on a component is a complex process that increases the costs of producing the component to an unwanted degree.
Another disadvantage of known capacitors is that a large amount of tantalum material is used for extending the tantalum sheet out of the anode body and housing and bending the tantalum sheet multiple times. This is disadvantageous because tantalum is a very expensive material.
In addition, known capacitors have the disadvantage that, on the one hand, the width of the tantalum sheet passing into the anode body determines the electrical properties of the capacitor and, on the other, the soldering surfaces on the underside of the housing, for reasons of standardization, must have specific, predetermined dimensions.
It is not always possible to adjust the electrical properties of the capacitor to the standard corresponding to the desired structural form, which results in related drawbacks in terms of production flexibility.